The best that any man can do is to estimate the factors as accurately as he can, judge as correctly as he can their interaction on each other, and then make his own conclusion or decision.
When a man can do this well in the ordinary affairs of life, he is said to be "a man of good judgment"; when he can do it well in a certain line of work--say investments in real estate--he is said to have good judgment in real estate.

The use of the word "judgment" here is excellent, because it expresses the act of a judge, who listens patiently to all the evidence in a case and then gives his decision.

And the act of the judge, and the act of any man in coming carefully to any decision, consist mainly in estimating the relative values of all the factors, and their relations to each other ("sizing them up" is the expressive slang), and then perceiving with more or less correctness what the answer is.

Some men do not have good judgment; some men highly educated, brilliant, and well-meaning, seem never to get quite the correct answer to any problem in life.

They are said to be unsuccessful and no one knows why.